1. Field of Invention
The invention relates to a fan and a fan housing thereof. In particular, the invention relates to a fan and a fan housing thereof that are capable of anti-backflow.
2. Related Art
As electronic devices provide better performance, operate at high frequencies and speeds and integrated in a smaller space, they generally generate more heat. The electronic devices are therefore likely to be unstable, lowering the reliability thereof. Therefore, heat dissipation becomes an important issue nowadays. Using a fan as a heat dissipating device is a common solution.
As shown in FIG. 1, a conventional anti-backflow fan 1 includes a fan body 11 and a fan housing 12. The fan body 11 is disposed inside the fan housing 12. Generally speaking, the fan body 11 has an impeller and a motor (not shown). The motor rotates the impeller to produce the airflow direction A as indicated in FIG. 1. The fan housing 12 is used to protect the fan body 11 and provide some fixing parts so that the magnetic conduction coils and circuit board of the motor can be fixed in the fan housing 12. Moreover, the fan housing 12 usually has several installation holes 121 for the user to fix the fan 1 on systems.
To prevent the airflow from leaking out of the air outlet 13 of the fan when the fan 1 becomes ineffective or non-operating, an anti-backflow device 14 is usually disposed on the air outlet 13 to stabilize the airflow field therein. In this case, the airflow is forbidden to enter the system via the air outlet 13.
The anti-backflow device 14 has a frame 141 and several anti-backflow sheets 142. The frame 141 is connected and fixed on the fan housing 12 by using the installation holes 121. The anti-backflow sheets 142 are pivotally installed on the frame 141 and cover the air outlet 13. When the fan 1 operates, the airflow passes through the air outlet 13, pushes the anti-backflow sheets 142 and then goes out. When the fan 1 stops operating, the anti-backflow sheets 142 cover the air outlet 13 to prevent backflows. However, although the anti-backflow device 14 can avoid backflows and thus stabilize the airflow field inside the system, the anti-backflow device 14 often uses the installation holes 121 of the fan 1 to connect to the fan housing 12. In that case, the installation holes 121 are not allowable for the user to use. The use of the fan 1 is thus limited. In addition, the anti-backflow device 14 and the fan housing 12 are two separate pieces. Not only are they likely to depart from each other, it also takes more product cost and time.
Therefore, it is desirable to provide an anti-backflow fan and the fan housing thereof to prevent backflows. The installation holes of the fan can be preserved for the user to use without increasing the size of the fan. The production cost and time can be significantly reduced, and the entire performance of the fan can be enhanced.